Yes, a TIP121 is too small for the current - assuming this is a 12V halogen. Personally, I'd just use a logic level Mosfet, like an IRL540, rather than a BJT.
ok, I tried to make it work now i have two questions:
1) transistore gets way too hot, is the mosfet not going to heat up?
2) transisotr does not get signal from arduino.... feels liek it's too weak. I tried to touch the base pin with a 9v batgtery and it works fine, i tired wit 5v and it works fine.... what can i do to amplify the power of a pin? maybe use a smaller transisotr that connnected to a 5v source?
Discussions
Best Answer 8 years ago
Yes, a TIP121 is too small for the current - assuming this is a 12V halogen. Personally, I'd just use a logic level Mosfet, like an IRL540, rather than a BJT.
Steve
Answer 8 years ago
yes, it's a 12v 75w halogen lamp.
what do you think about the tip305it dissipates 80w.
I am a begginer and have little knowledge of electronics...
(what's the difffernece between a msfet and a bjt?)
Answer 8 years ago
You really don't want to dissipate 80 W if you can help it. The Mosfet will waste much less heat - like 0.6 W when its on.
A mosfet uses a VOLTAGE on its GATE terminal to control current flowing between source and drain.
A BJT uses a CURRENT on its BASE terminal to control current flowing between collector and emitter.
Answer 8 years ago
ok, I tried to make it work now i have two questions:
1) transistore gets way too hot, is the mosfet not going to heat up?
2) transisotr does not get signal from arduino.... feels liek it's too weak. I tried to touch the base pin with a 9v batgtery and it works fine, i tired wit 5v and it works fine.... what can i do to amplify the power of a pin?
maybe use a smaller transisotr that connnected to a 5v source?
thank you
Answer 8 years ago
Why did you remove the best answer that you'd given me ?
Answer 8 years ago
No, the MOSFET won't get as hot.
Put a resistor from +5 to the pin of the arduino, then to the base/gate terminal- something like 330 Ohms should work nicely.
Arduino pins don't source much current.
Steve